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In-situ synthesized TiB2/6061 composites were prepared from Al-K2TiF6-KBF4 by high energy ball milling and stir casting. Phase analysis and microstructure observation of the samples were characterized by XRD, SEM and EDS, respectively. The effect of TiB2 particle content on the microstructure, tensile properties and wear resistance of the composites was studied. The results show that the average size of TiB2 particles is 1 μm, which is polygonal shape. The average grain size of the composites can be refined significantly as the TiB2 particle mass content increased from 1 to 3%; however, the grain coarsening occurs in the 5 wt.% TiB2/6061composites. The 3 wt.% TiB2/6061 composites have best tensile strength, yield strength and Young’s modulus among the composites in ranges of the TiB2 mass fraction from 1 to 5%. Strengthening mechanisms of the TiB2/6061 composites were fine grain strengthening, Orwan strengthening and CTE strengthening, in which the CTE strengthening plays an important role as increasing the TiB2 content. The pin-on-disk wear test results indicated that the average friction coefficient and wear rate of the TiB2/6061 composites increased firstly and then decreased with increasing the TiB2 content from 1 to 5 wt.%. The wear mechanism of the TiB2/6061 composites was discussed.

Ternary compound CuSbSe2-alloyed PbTe, CumPb100SbmTe100Se2m (CLAST), presents outstanding n-type thermoelectric transport behavior and features hierarchical Cu-based precipitates and interstitials that can balance phonon and carrier transport. Results show that a small amount of CuSbSe2 (∼3%) alloying in CLAST can realize a room-temperature carrier concentration of ∼1.7 × 1018 cm−3 and then optimize the power factor, and simultaneously precipitate out embedded Cu-based nanostructures in the matrix to lower the lattice thermal conductivity. Additionally, extra Cu atoms adding in CLAST can form interstitials and further improve both the carrier concentration to ∼3.0 × 1018 cm−3 and carrier mobility to ∼1227.8 cm2 V−1 s−1 at room temperature, which benefits a maximum power factor of ∼20.0 μW cm−1 K−2 in Cu3.3Pb100Sb3Te100Se6. Moreover, the Cu interstitials together with massive Cu-based nanoprecipitates can strongly scatter a wide set of phonons, and largely lower the lattice thermal conductivity to ∼0.44 W m−1 K−1 in Cu3.4Pb100Sb3Te100Se6 at 623 K. Finally, these Cu-based hierarchical structures in CLAST samples can synergistically optimize the phonon and carrier transport properties and contribute to a high ZT of ∼0.5 at 300 K and a peak ZT of ∼1.4 at 723 K. A remarkably high ZTave of ∼0.94 at 300–723 K is achieved in Cu3.3Pb100Sb3Te100Se6 due to high ZT values in the low temperature range, outperforming other high-performance n-type PbTe-based thermoelectric materials.

Gold clusters are considered as widely used catalyst for chemical industry, but the efficiency of catalyst has been limited by the aggregation of the gold atoms, since the active sites are only loc...

In this study, tobermorite was successfully synthesized from two kinds of industrial wastes by single step hydrothermal method. The structural and morphological changes during synthesis show that well-crystallized tobermorite can be obtained within 6 h at 180 °C in this system. The carbon impurities lead to a longer synthesis time and lower crystallinity of tobermorite. The tobermorite displays attractive adsorption capacity for Cr3+ (4.87 mmol/g), which is 2–3 times higher than common clay minerals. Meanwhile, Cr3+ adsorption causes the exsolution of structural Ca2+ in tobermorite channels, leading to the damage of crystallinity and decrease in sorption capacity of adsorbent. Therefore, better crystallization of tobermorite is helpful to achieve higher sorption capacity for Cr3+. These results indicate tobermorite can be used in industrial processes to adsorb heavy metals from wastewater.

The n-type PbTe still maintains relatively low thermoelectric performance compared with its p-type counterpart. Thus, to promote its performance in n-type PbTe, we conduct successive strategies that firstly suppressing the lattice thermal conductivity (κlat) through alloying with ternary compound AgSbSe2, and then optimizing carrier density with Sb, Bi or I doping. In AgSbSe2-alloyed PbTe samples, the κlat can be evidently reduced, and the minimum κlat decreases from ∼1.1 Wm−1K−1 in undoped PbTe to ∼0.8 Wm−1K−1 in PbTe–5%AgSbSe2. Based on PbTe–5%AgSbSe2 matrix, several dopants (Sb, Bi or I) are used to optimize its carrier density, and found that I element is verified to be the most effective dopant to enhance its electrical transport properties. In I-doped PbTe–5%AgSbSe2 samples, the carrier density raises from ∼2.49 × 1016 cm−3 in PbTe–5%AgSbSe2 to ∼1.15 × 1019 cm−3 in PbTe0.992I0.008-5%AgSbSe2, which contributes to the maximum power factor ∼14.8 μWcm−1K−2. Combining the reduced lattice thermal conductivity and improved power factor, the maximum ZTmax and average ZTave values in PbTe0.992I0.008-5%AgSbSe2 are boosted to ∼1.0 at 723 K and ∼0.77 at 300–823 K, respectively. This work points out a valid avenue to improve thermoelectric transport property in n-type PbTe with separately successive strategies to adjust its thermal and electrical performance.

PbTe-based thermoelectric materials are considered to be a medium-temperature thermoelectric candidates and the high-performance n-type PbTe is urgently to be developed to match its p-type counterpart on account of practical application. Herein, we firstly optimized the carrier density of n-type PbTe through Sb doping, and obtained a maximum ZT value of ∼1.0. Then, based on the optimized carrier density, we introduced ternary compounds AgSb(Se, Te)2 to suppress the lattice thermal conductivity. Minimum lattice thermal conductivity of n-type PbTe was reduced as low as ∼0.53 W m−1K−1 and ∼0.62 Wm−1K−1 through introducing AgSbSe2 and AgSbTe2, respectively. Combining the maintained electrical properties with suppressed thermal conductivity, maximum ZT values ∼1.2 and ∼1.3 were obtained in PbTe+2%AgSbSe2 and PbTe+2%AgSbTe2, respectively. This work provides an effective strategy of synergistically balancing charge and phonon transports in n-type PbTe with ternary AgSb(Se, Te)2 compounds.

Two-dimensional (2D) ultrathin silicon nanosheets (Si NSs) were synthesized by DC arc discharge method and investigated as anode material for Li-ion batteries. The 2D ultrathin characteristics of Si NSs is confirmed by means of transmission electron microscopy (TEM) and atomic force microscopy (AFM). The average size of Si NSs is about 20 nm, with thickness less than 2.5 nm. The characteristic Raman peak of Si NSs is found to have an appreciable (20 nm) shift to low frequency, presumably due to the size effect. The synergistic effects of Ar(+) and H(+) lead to 2D growth of Si NSs under high temperature and energy. Electrochemical analyses reveal that Si NSs anode possesses stable cycling performance and fast diffusion of Li-ions with insertion/extraction processes. Such Si NSs might be a promising candidate for anode of Li-ion batteries.